Abolition of aorticorenal ganglia pacing responses improves denervation efficacy

Abstract

BACKGROUND: Transcatheter renal denervation (RDN) remains inconsistent despite developments in ablation technologies, due to the lack of an intraprocedural physiological end point. OBJECTIVES: To identify whether aorticorenal ganglion (ARG) guided RDN using microwave (MW) catheter leads to more consistent denervation outcomes compared with empirical MW ablation. METHODS: Pigs underwent sham procedure (n=8) or bilateral RDN using an in-house built open-irrigated MW catheter. Before denervation, ipsilateral ARG pacing was performed leading to renal artery vasoconstriction. MW ablation group (MW-group; n=7) received 1 ablation (100-120 W for 360 seconds) in the mid-main renal artery based on artery caliber. ARG-guided-MW ablation group (ARG-MW-group; n=7) was permitted an additional ablation more distally or at higher power until a vasoconstrictive response was abolished. Animals were euthanized at 4 to 5 weeks post-procedure. RESULTS: ARG pacing caused an ipsilateral reduction in renal artery caliber from 4.67 to 4 mm; P=0.0006 in MW-group and 4.8 to 3.9 mm; P=0.001 in ARG-MW-group. Repeat ARG pacing at euthanasia led to a reduction in renal artery caliber in MW-group from 5.1 to 4.8 mm; P=0.006, but not in ARG-MW-group from 4.88 to 4.55 mm; P=0.08. There were no differences in ablation injury volumes between the groups. Compared with undenervated sham controls, ARG-MW-RDN versus MW-RDN caused median reductions in viable nerve area (antityrosine hydroxylase staining) at 4 to 5 weeks by 92.6% (interquartile range, 0.94-19.59%; P<0.0001) versus 55.02% (interquartile range, 15.87-75.11%; P=0.006) and median renal cortical norepinephrine content by 68.06% (interquartile range, 27.16-38.39%; P<0.0001) versus 25.25% (interquartile range, 56.97-157.7%; P=NS). CONCLUSIONS: ARG pacing serves as a physiological procedural end point to guide MW denervation to improve denervation outcomes.